1. Field of the Invention
The present invention relates to an information processing apparatus that has a plurality of operating modes including a power saving mode and to a control method thereof.
2. Description of the Related Art
With regard to power saving in an information processing apparatus, measures are being considered for suppressing power consumption by reducing power supply to hardware not being used when the information processing apparatus is idle. An operating mode in which power consumption is decreased relative to normal operation is called a power saving mode.
For example, Japanese Patent Application Laid-Open No. 2004-074621 proposes a technique of reducing power supply to nonvolatile memory such as the hard disk of an information processing apparatus in power saving mode, in order to reduce power consumed by nonvolatile memory.
Recent information processing apparatuses have started employing a general-purpose operating system (hereinafter, general-purpose OS). Many general-purpose OSs access the hard disk at an arbitrary time. Consequently, with an information processing apparatus employing a general-purpose OS, power still needs to be supplied to the hard disk in power saving mode, preventing power consumption from being sufficiently reduced.
In the case of a general-purpose OS having a demand paging function of only allocating memory pages that have been accessed to physical memory, for example, anticipating when the text area of an executable file or a library will be loaded from a file can be difficult. Also, in the case of a general-purpose OS having a swap function of saving data that does not fit in memory to hard disk, anticipating the swap in and swap out timing can be difficult. Further, while many open source applications can generally be used with a general-purpose OS, completely ascertaining and regulating the file access timing of these applications can be difficult. Thus, in an information processing apparatus employing a general-purpose OS, power supply to nonvolatile memory cannot be reduced even when operating in power saving mode. Consequently, power needs to be supplied to both nonvolatile memory and blocks controlling nonvolatile memory, preventing power consumption from being sufficiently reduced even in power saving mode.